SHDSL features symmetrical data rates in both the upstream and downstream directions, from 192 kbit/s to 2,312 kbit/s of payload in 8 kbit/s increments for one pair and 384 kbit/s to 4,624 kbit/s in 16 kbit/s increments for two pairs of wires. The reach varies according to the looprate and noise conditions (more noise or higher rate means decreased reach) and may be up to 3,000 meters. The two pair feature may alternatively be used for increased reach applications by keeping the data rate low. Halving the data rate per pair will provide similar speeds to single pair lines while increasing the error/noise tolerance.

An optional extended SHDSL mode allows symmetric data rates up to 5,696 kbit/s on one pair, using the 32-TC-PAM modulation scheme specified in Annexes F and G. Using M-pair bonding, up to four pairs of wires may be bonded to yield data rates up to M×5,696 kbit/s. In this way, a single SHDSL interface using four bonded wire pairs can carry up to 22,784 kbit/s.

The industry standard for SHDSL is defined by ITU-T recommendation G.991.2. This was first published in February 2001. SHDSL equipment is also known by the standard's draft name of G.SHDSL. Major updates to G.991.2 were released in December 2003. Equipment conforming to the 2003 version of G.991.2 is often referred to by the standard's draft name of G.SHDSL.bis or just SHDSL.bis. The updated G.991.2 features:

Optional support for up to four copper pair connections (M-pair)

Optional extensions to allow user data rates up to 5696 kbit/s per pair, described in Annexes F and G

Optional support for dynamic rate repartitioning, allowing flexible change of the SHDSL data rate without service interruption, described in Annex E.10.3

New payload definitions including Ethernet packet transfer mode (PTM), described in Annex E.11